Method and apparatus for time advance validation using reference signal received power

ABSTRACT

There is provided a method and user equipment that enable the evaluation of the validity of a timing advance known to a UE for enabling the UE to transmit using preconfigured uplink resources (PUR). The method includes receiving data enabling determination of a measured change in a reference signal received power by a UE. The UE subsequently determines if the measured change in the RSRP is less than a positive change threshold. If the determination is true, the UE proceeds with the transmission using PUR. In some embodiments, prior to proceeding with the transmission, the UE further evaluates or determines if the measured change in the RSRP is greater than a negative change threshold. The UE will subsequently use PUR for the transmission only if the measured change in the RSRP is greater than a negative change threshold.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. PatentApplication Ser. No. 62/805,174 entitled “Method and Apparatus for TimeAdvance Validation Using Reference Signal Received Power” filed Feb. 13,2019, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention pertains to the field of telecommunications and inparticular to methods and apparatuses for time advance validation.

BACKGROUND

Currently, whenever a user equipment (UE) has data to transmit from idlemode, it must execute the random-access procedure or random accesschannel (RACH) procedure which requires several messages and lots ofsignalling overhead. The uplink transmission procedure for a UE in radioresource control (RRC) idle mode is shown in FIG. 1.

Hence, in 3GPP, a new work item has been proposed in RP-181450 inrelation to Rel-16 machine type communication (MTC) enhancements forlong term evolution (LTE) with an objective of improving uplink (UL)transmission efficiency and/or UE power consumption. The objective isdefined as specifying support for transmission in preconfiguredresources in idle and/or connected mode based on SC-FDMA waveform forUEs with a valid timing advance.

For 3GPP, it has already been agreed that this objective would beaccomplished by supporting the transmission in preconfigured ULresources (PUR) in idle mode so that a UE can skip legacy RACHprocedures and start transmission when its PUR is allocated. However, animportant aspect related to PUR transmissions is the timing advance(TA). As defined in the objective, the UE can only transmit on PUR if ithas a valid timing advance. When a UE moves, the TA will change, thusfor mobile UEs, a UE must make sure that it has a valid TA before doinga PUR transmission.

It is known that TA is the amount of time it takes for an eNBtransmission to reach the UE plus the amount of time it takes the UE'stransmission to reach the eNB. In legacy RACH procedure, the TA ismeasured by the eNB from the PRACH (msg1 101) and then sent to the UE inthe random-access response (RAR) (msg2 102). Also, while the UE is inconnected mode, the eNB can continuously adjust the UE's TA via anygrant message.

3GPP has made some high-level progress with respect to the TA validationmechanism. For example, an agreement has been reached that in idle mode,at least the following TA validation attributes are supported: 1)Serving cell changes (wherein a serving cell is the cell that the UE iscamping on); 2) Time alignment timer for idle mode; 3) Serving cell RSRPchanges can be based on the RSRP measurement definition in existing 3GPPRelease 15 TS 36.214.

The reference signal received power (RSRP) is defined as the averageover the power contributions of the resource elements that carrycell-specific reference signals within the considered measurementfrequency bandwidth. For RSRP determination, the cell-specific referencesignal R0 is to be used. If the UE can reliably detect thatcell-specific reference signal R1 is available, it may use R1 inaddition to R0 to determine RSRP.

A change in the RSRP, ΔRSRP, measured by the UE is indicative of achange of a distance Δd from the eNB. This change Δd indicates a changein the propagation delay between the UE and the eNB. If this propagationdelay exceeds a certain value, the TA currently known to the UE needs tobe updated.

As such, a particular problem relates to how to use the RSRPmeasurements to validate the TA. A first way that RSRP is to compare the“ΔRSRP_Measured” with a predefined threshold “ΔRSRP_Threshold”, forexample as given in Equation 1:

Abs(ΔRSRP_Measured)>ΔRSRP_Threshold  (1)

If the Equation 1 is true, the UE's current TA is invalid and the UEcannot do a PUR transmission and will fall back to a legacy transmissionin order for the UE to receive a new valid TA. However, it has beendetermined that this method is highly inaccurate as ΔRSRP_Measured willdepend on the distance from the eNB.

Accordingly, there may be a need for a method and apparatus for timeadvance validation that is not subject to one or more limitations of theprior art.

This background information is intended to provide information that maybe of possible relevance to the present invention. No admission isnecessarily intended, nor should be construed, that any of the precedinginformation constitutes prior art against the present invention.

SUMMARY

It is an object of the present invention to obviate or mitigate at leastone disadvantage of the prior art.

According to an aspect of the present invention, there is provided amethod for the evaluation of the validity of a timing advance known to aUE for enabling the UE to transmit using preconfigured uplink resources(PUR). The method includes receiving, by a UE, data enablingdetermination of a measured change in RSRP and upon determination thatthe measured change in the RSRP does not exceed a positive changethreshold, transmitting, by the UE, using PUR.

In some embodiments, the method further includes, only upondetermination that the measured change in the RSRP does not exceed anegative change threshold, transmitting, by the UE, using PUR. In someembodiments, one or both of the positive change threshold and thenegative change threshold are defined for a specific UE. In someembodiments, a single threshold is used as the positive change thresholdand the negative change threshold. In some embodiments, the positivechange threshold and the negative change threshold have the same value.

According to another aspect of the present invention there is provided aUE including a processor and a non-transient memory for storinginstructions. The instructions, when executed by the processor cause theUE to be configured to receive data enabling determination of a measuredchange in RSRP and upon determination that the measured change in theRSRP does not exceed a positive change threshold, transmit using PUR.

In some embodiments, the instructions, when executed by the processorcause the UE to be configured to, only upon determination that themeasured change in the RSRP is less than a negative change threshold,transmit using PUR. In some embodiments, one or both of the positivechange threshold and the negative change threshold are defined for aspecific UE.

Embodiments have been described above in conjunction with aspects of thepresent invention upon which they can be implemented. Those skilled inthe art will appreciate that embodiments may be implemented inconjunction with the aspect with which they are described but may alsobe implemented with other embodiments of that aspect. When embodimentsare mutually exclusive, or are otherwise incompatible with each other,it will be apparent to those skilled in the art. Some embodiments may bedescribed in relation to one aspect, but may also be applicable to otheraspects, as will be apparent to those of skill in the art.

Some aspects and embodiments of the present invention may provide aqualification of whether the UE has a valid TA so that it is capable ofcontinuing to use PUR.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the present invention will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1 illustrates an uplink transmission procedure for a UE in radioresource control (RRC) idle mode according to the prior art.

FIG. 2 illustrates a method for evaluation of the validity of a timingadvance for enabling use of preconfigured uplink resources (PUR), inaccordance with embodiments.

FIG. 3 illustrates ΔRSRP as a function of the initial distance d_(i)from the eNB according to embodiments.

FIG. 4 illustrates abs(ΔRSRP_measured) as a function of the initialdistance d_(i) for a UE moving 705 m towards and away from eNB,according to embodiments.

FIG. 5 is a schematic diagram of an electronic device according toembodiments.

DETAILED DESCRIPTION

As previously noted, if the Equation 1 is true, the UE's current TA isinvalid and the UE cannot do a PUR transmission and will fall back to alegacy transmission in order for the UE to receive a new valid TA.However, it has been determined that this method is highly inaccurate asthe magnitude of ΔRSRP_Measured will vary depending on the distance fromthe eNB. The TA value will vary proportionally to distance from the eNB.As such, a single threshold for positive and negative changes of RSRPwill correspond to different TA change amounts when the UE is movingcloser to the eNB and further away from the eNB. A single thresholdappropriate for one direction appropriate for one direction of TA changeis therefore highly inaccurate for the other direction of TA change.

There is provided a method and user equipment that enable the evaluationof the validity of a timing advance known to a UE for enabling the UE totransmit using preconfigured uplink resources (PUR). The method includesreceiving data enabling determination of a measured change in areference signal received power by a UE. The UE subsequently determinesif the measured change in the RSRP exceeds a positive change threshold.If the determination is that the positive threshold has not beenexceeded, the UE proceeds with the transmission using PUR.

For example, the UE receives a signal containing data from the eNB,wherein measurements can be made on the signal in order to obtain anindication of the current RSRP. The UE can subsequently compare thismeasured RSRP with the previously measured RSRP in order to determine ameasured change in the RSRP.

In some embodiments, prior to proceeding with the transmission, the UEfurther evaluates or determines if the measured change in the RSRPexceeds a negative change threshold. The UE will subsequently use PURfor the transmission only if the measured change in the RSRP does notexceed the negative change threshold.

FIG. 2 illustrates a method for the evaluation of the validity of atiming advance known to a UE for enabling the UE to transmit usingpreconfigured uplink resources (PUR). The method includes the UEreceiving data enabling determination of a measured change in areference signal received power (RSRP) 210. The UE will subsequentlyevaluate the measured change and determine if the measured change in theRSRP is less than a positive change threshold 220. Upon a determinationthat the RSRP is less than the positive change threshold the UEconsiders the timing advance to be valid and subsequently transmitsusing preconfigured uplink resources (PUR) 240.

In some embodiments, the UE further determines if the measured change inthe RSRP is greater than a negative change threshold 230. Upon adetermination that the RSRP is greater than the negative changethreshold the UE considers this as further validation that the timingadvance and can thus transmitting using PUR is appropriate.

In some embodiments, when the positive change threshold is determined tobe negative or the negative change threshold is determined to bepositive, the method further includes receiving by the UE from theevolved Node B (eNB) a transmission indicating nonuse of RSRP for TAvalidation 250.

In some embodiments, when the positive change threshold is determined tobe negative or the negative change threshold is determined to bepositive, the method further includes using by the UE, RACH mechanisms260 for configuring uplink resources for transmissions.

For example, if the positive change threshold or the negative changethreshold are exceeded the UE is configured for non-transmission usingPUR. If either of the thresholds are exceeded, the UE is configured touse RACH mechanisms in order to configure uplink resources fortransmissions.

For further clarity, according to embodiments, a UE is given a TA valuematching its known location, by the eNB when the PUR is configured. TheUE will save a current self-measured RSRP as a starting reference RSRPassociated with the TA value provided by the eNB. A current and possiblydifferent TA value is also a component of response messages received bythe UE after each UE PUR transmission. In some embodiments, the UE iseither provided a single RSRP change threshold value or the UE mayalternatively be provided an upper threshold and a different lowerthreshold. The RSRP change thresholds correspond to the individual TAvalue provided at PUR configuration and each update thereto. In order toderive the RSRP thresholds that match a TA, the eNB can determineappropriate D RSRP value(s) for the particular UE or less accurategeneric values for all UEs for the particular TA. At a time X just priorto a UE being scheduled to transmit PUR, the UE will determine thecurrent RSRP. It is noted that this determined current RSRP is notprovided by the eNB. At time X, the UE performs the comparison test(s)to see if the RSRP change since when the UE was configured for PUR orlast updated for PUR, exceeds what has been set as a threshold. If theRSRP has changed too much the UE does not transmit. The UE performs aRACH procedure to obtain a new TA and also new RSRP threshold(s).Alternatively, if the RSRP has not changed such that the one or more ofthe thresholds are exceeded, the UE transmits on the PUR previouslyassigned thereto.

According to some embodiments, rather than the eNB determining the RSRPchange thresholds at each TA configuration for updating the UE, the eNBcan determine the RSRP change thresholds in advance and build a tableassociating or correlating the RSRP change thresholds with the TAs.Having done this the eNB could reference the table in order to obtainthe RSRP change thresholds to accompany the TA when communicating withthe UE. The eNB could alternatively send the whole table to the UE atthe time of initial configuration and the UE can save this table forfuture reference. This embodiment can allow the eNB to only send the TAupdates in the PUR responses and the UE would subsequently look up theRSRP change thresholds that match the given TA.

In some embodiments, the UE can calculate the RSRP change thresholdseither on an as needed basis or in advance and subsequently save thisinformation in a table, or similar configuration, associating orcorrelating TAs with the RSRP change thresholds. In this embodiment, theeNB would only need to send the TA value and the UE would be capable ofderiving the matching RSRP change thresholds either on an as neededbasis or by reference to the saved table determined in advance. In suchan embodiment, the eNB would need to provide the UE with information inorder for it to complete the above defined calculations.

According to another embodiment, the UE is given, for example by theeNB, one or more RSRP change thresholds, for example in a table format,paired with TA values at the time of PUR configuration. According toother embodiments, the UE can be configured to determine RSRP thresholdsthat match the respective TAs.

As noted above, it is understood that if Equation 1 is true, the UE'scurrent TA is invalid and the UE cannot do a PUR transmission and willfall back to a legacy transmission in order for the UE to receive a newvalid TA. Furthermore, also as noted above it has been determined thatthis method is highly inaccurate as ΔRSRP_Measured will depend on thedistance from the eNB. Accordingly, it has been determined that a singlethreshold for the determination of TA validity can be used, however itmay not be the most accurate.

It has been determined that measured RSRP in dB can be generalized as:

RSRP(d _(i))=P _(tx)−PL(d _(i))  (2)

-   -   where: P_(tx) is the eNB transmit power; d_(i) is the distance        from eNB; and PL is the path loss.

Path loss equations in dB usually take the form:

PL(d _(i))_(dB) =k log₁₀(d _(i))+X  (3)

-   -   where: k and X depend on many practical elements such as antenna        height and environment (e.g. urban, sub-urban, rural); and d_(i)        is the distance between the UE and the eNB.

Some examples of path loss equations are defined below:

NLOS urban, suburban, and rural macro path loss equation can be definedas:

PL(d _(i))=161.04−7.1 log₁₀(W)+7.5 log₁₀(h)−(24.37−3.7(h/h_(BS))²)log₁₀(h _(BS))+(43.42−3.1 log₁₀(h _(BS)))(log₁₀(d _(i))−3)+20log₁₀(f _(c))−(3.2(log₁₀(11.75h _(UT)))²−4.97)

This path loss equation, when re-written in the form of “[[k]]log₁₀(d_(i))+{{X}}” form is represented as, wherein k is surrounded bydouble square brackets and X is surrounded by double curly brackets:

PL(d _(i))=[[(43.42−3.1 log₁₀(h _(BS)))][(log₁₀(d _(i))+{{161.04−7.1log₁₀(W)+7.5 log₁₀(h)−(24.37−3.7(h/h _(BS))²)log₁₀(h _(BS))−3*(43.42−3.1log₁₀(h _(BS))+20 log₁₀(f _(c))−(3.2(log₁₀(11.75h _(UT)))²−4.97)}}

-   -   where, W is the street width; h is the average building height;        h_(BS) is the eNB antenna height; h_(UT) is the UE antenna        height; and f_(c) is the center frequency in Hz.

Given the above, the path loss for an urban micro non-line of sight(NLOS) hexagonal cell layout can be defined as: PL(d_(i))=[[(36.7)]](log₁₀ (d_(i))+{{26 log₁₀(f_(c))+22.7}}.

The path loss for an indoor hot spot NLOS path loss can be defined as:PL(d_(i))=[[(43.3)]] (log₁₀(d_(i))+{{20 log₁₀(f_(c))+11.5}}.

The path loss for a free space can be defined as: PL(d_(i))=[[(20)]](log₁₀ (d_(i))+{{20 log₁₀(f_(c))−147.55}}.

Having regard to the above examples, it is noted that the term {{X}} inall the above equations does not depend on d_(i). Accordingly, the RSRPequation can be generalized as given in Equation 4.

RSRP(d _(i))=P _(tx) −k log₁₀(d _(i))−X  (4)

If it is considered that a UE moves a distance Δd, the UE willexperience a change in the RSRP that can be expressed as defined inEquation (5).

ΔRSRP(d _(i))=(P _(tx) −k ₂ log₁₀(d _(i))−X ₂)−(P _(tx) −k ₁ log₁₀(d_(i) ±Δd)−X ₁)  (5)

Furthermore, assuming the path loss equation remains constant from d_(i)to d_(i)±Δd then k₁=k₂ and X₁=X₂, and Equation 5 can be simplified toEquation 6.

ΔRSRP(d _(i))=k(log₁₀(d _(i) −±Δd)−log₁₀(d _(i)))  (6)

Where: +Δd is for a UE moving away from the eNB; and −Δd is for a UEmoving towards the eNB.

As can be determined from the above equations, ΔRSRP depends on both Δdand d_(i). Accordingly, it has been determined that a constant ΔRSRPthreshold, for example, will not work well across a broad cell radius.

FIG. 3 illustrates ΔRSRP as a function of the initial distance d_(i)from the eNB according to embodiments. FIG. 3 shows this dependencywhere the measured ΔRSRP is plotted against the initial distance fromthe eNB (d_(i)) for the free space path loss 225 and the urban macroNLOS path loss models 245 for a UE that is moving away from the eNB.These models were chosen as they represent the two extremes of wirelessenvironments.

FIG. 4 represents data that has been determined assuming a constantdistance Δd=705 meters with the UE moving away from the eNB, whichsubstantially corresponds to a one cyclic prefix timing error in the TA.It has been determined that a further issue with using a singlethreshold as noted in Equation 1, is that the abs(ΔRSRP_Measured) isvery different if the UE moves towards the eNB vs the UE moving awayfrom the eNB. The abs(ΔRSRP_measured) as a function of the initialdistance d_(i) for a UE moving 705 m towards and away from eNB isillustrated in FIG. 4. It can be seen that there is a very cleardifference in the abs(ΔRSRP_Measured) for free space path loss between aUE moving towards the eNB 340 and UE moving away from the eNB 320.

According to embodiments, it is assumed that the change in RSRP isdefined:

ΔRSRP_Measured=RSRP_reference−RSRP_current  (7)

Where: RSRP_reference is the RSRP measured when the TA was given to theUE; and RSRP_current is the RSRP measured when the TA is beingevaluated.

Having regard to Equation 7, if RSRP_reference is −60 dBm andRSRP_current is −50 dBm, ΔRSRP_Measured is −10 dB. In addition, ifRSRP_reference is −60 dBm and RSRP_current is −70 dBm, ΔRSRP_Measured is+10 dB.

Furthermore, if the UE moves closer to the eNB, then the ΔRSRP_Measuredwill be negative and ΔRSRP_Measured will be positive if the UE movesaway from the eNB. At the same initial distance from the eNB, theabsolute value of the ΔRSRP_Measured will be larger when moving closerto the eNB than the absolute value of the ΔRSRP_Measured when movingaway from the eNB. This can be seen with reference to FIG. 4.

According to embodiments, two thresholds will be needed in order toevaluate if TA is valid. According to embodiments, a first threshold isΔRSRP_ThNeg which applied to the case where the UE moves towards theeNB. According to embodiments, a second threshold is ΔRSRP_ThPos whichis applied to the case when the UE moves away from the eNB.

According to embodiments, the UE will evaluate the TA validity using thefollowing condition:

ΔRSRP_ThNeg<ΔRSRP_Measured<ΔRSRP_ThPos  (8)

According to embodiments, if the condition as defined by Equation 8 isnot met, then the TA currently known to the UE is invalid.

As an example, let d_(i) be the distance from the eNB when the TA wasgiven to the UE. The MaxAllowedΔd is considered as the maximum allowedUE movement towards or away from the eNB for which the TA is stillvalid.

In the example when the d_(i) is less than the MaxAllowedΔd (forexample, when UE is closer to the eNB than the MaxAllowedΔd, which willbe readily understood to be a distance change threshold), any movementtowards the eNB will not invalidate the TA. So, the UE only needs toevaluate a positive ΔRSRP_Measured as follows:

ΔRSRP_Measured<ΔRSRP_ThPos  (9)

It is considered that if the condition as defined in Equation 9 is notmet, then the TA is invalid.

According to some embodiments, the UE is configured to determine theabove noted thresholds, namely ΔRSRP_ThPos and ΔRSRP_ThNeg. When the UEreceives a TA value from the eNB, the UE is configured to determineΔRSRP_ThPos using Equation 10.

ΔRSRP_ThPos=k(log₁₀(d _(i)+MaxAllowedΔd)−log₁₀(d _(i)))−Z_(margin)  (10)

In addition, if (di−MaxAllowedΔd)>0) then ΔRSRP_ThNeg is determinedusing Equation 11 and Equation 8 is used to determine if the TA isvalid.

ΔRSRP_ThNeg=k(log₁₀(d _(i)−MaxAllowedΔd)−log₁₀(d _(i)))+Z_(margin)  (11)

However, if (d_(i)−MaxAllowedΔd)>0) is not met, then Equation 9 is usedto determine if the TA is valid.

According to embodiments, ΔRSRP_ThNeg should be a negative value andΔRSRP_ThPos should be a positive value. The above calculation ofΔRSRP_ThNeg and ΔRSRP_ThPos only needs to occur when the TA is updatedby the eNB which will be infrequent and accordingly there are likelyminimal concerns of microprocessor capability (MIPS) without the needfor interlocked pipelined stages or additional UE power consumption forperforming these calculations. It is understood that the UE will have toperform the “log” function but this is considered to be within the UEcapabilities since RSRP is reported in dB.

According to embodiments, the term Z_(margin) creates a margin formeasurement errors which minimize the UE errors regarding updating theTA when it is was not needed vs. using an invalid TA. It is understoodthat using an invalid TA is a worse scenario when compared with updatingthe TA when it is was not needed. It is understood that the RSRP intrafrequency relative accuracy for UE category M1 with coverage enhancement(CE) mode A for half duplex frequency division duplex (HD-FDD) can be ashigh as 4 dB. Also, it is considered that the TA measurement of the eNBwill not be perfect so d_(i) will have error. A dramatic change of theenvironment from position d_(i) to d_(i)+Δd is also a source for error.The amount of margin (e.g. Z_(margin)) to add is up to the eNB so theeNB could broadcast a Z_(margin) via system information since the eNBwould be cell/sector specific or could inform the UE via directsignalling.

According to embodiments, the UE can calculate d_(i) based on the lastvalid TA based on Equation 12:

d _(i)=TA×c/2  (12)

Where: c is the speed of light

According to embodiments, as previously disclosed, k is a constant thatis propagation conditions specific, for example k depends on one or acombination of topology and configuration of the cell. For example, insome embodiments k=20 for free space; k=36.7 for hexagonal cell layouturban micro NLOS; k=43.1 for indoor NLOS. As would be readily understoodother values for varying configuration, topologies of the cell may beused and the above are merely to be considered as examples.

According to embodiments, the propagation conditions which the eNB'scell/sector covers would be known a priori so the eNB could broadcast kvia system information since it would be cell/sector specific or couldinform the UE via direct signalling.

According to embodiments, Δd relates to the amount of timing error theeNB can tolerate. As an example, a maximum allowed timing error can bedetermined according to Equation 13:

Maximum allowed Timing Error=2*MaxAllowedΔd/c  (13)

For example, a MaxAllowedΔd=705 meters corresponds to 4.7 us which isthe normal cyclic prefix (CP). The amount of timing error the eNB cantolerate depends on the eNB implementation which can be considered to beconstant and also known a priori in order that the eNB can broadcast Δdto the UE, for example using system information as Δd would be cellspecific or the eNB can inform the UE via direct signalling.

According to some embodiments, when d_(i) gets large and Z_(margin) isnon-zero, it is possible that ΔRSRP_ThPos becomes negative orΔRSRP_ThNeg to be positive which means the UE can't reliably determineif the TA is valid based on RSRP. In an instance wherein after the eNBmeasures the TA, the eNB can calculate the thresholds and if eitherΔRSRP_ThPos is negative or ΔRSRP_ThNeg is positive for the positiond_(i), the eNB can inform UE to not use RSRP to validate TA or the eNBcan disable PUR transmissions for that UE and inform the UE to uselegacy RACH mechanisms. If the UE gets closer to the eNB, the eNB thenre-enable PUR transmissions.

According to embodiments, for both informing the UE to not use RSRP tovalidate TA or disabling PUR transmissions for that UE and inform the UEto use legacy RACH mechanisms, these actions can be taken by the eNBwithout explicit signalling to the UE because the UE will alsoautonomously determine that the ΔRSRP_ThPos is negative or ΔRSRP_ThNEgis positive and thus the UE, based on pre-configuration, can assume oneof these actions will be taken by the eNB.

According to embodiments, the eNB can adjust the values of k and Δdbased on the success or failure of the TA validation. For example, ifthe eNB observes that UEs are using invalid TA more frequently thandesired, for example greater than 1% of the time, across the entirecell, the eNB can perform one or more actions including decreasing Δdand increasing Z_(margin). For example, if the eNB observes UEs that arefar away from the eNB are using an invalid TA more frequently than UEsclose to the cell, k can be increased. According to embodiments, thisconfiguration of the eNB may be left to be determined based on thespecific implementation of the eNB, and thus specifically requiring thisconfiguration for the eNB may not be required.

According to some embodiments, the eNB or the UE is configured to creategeneralized threshold functions, for example one for the positivethreshold and one for the negative threshold.

According to some embodiments, the generalized threshold functions canbe learned. For example, the generalized threshold functions can beevaluated based on a plurality of data indicative of previous TA updatesand RSRP updates. The generalized threshold functions can be evaluatedfor example by the following process. Initially a function whichestimates the expected RSRP value at different distances ‘d’ is created.This can be estimated or evaluated from the historical TA updates andRSRP updates in the cell for all of the UEs serviced by that cell. Eachtime the eNB updates the TA of a UE, the eNB can request the RSRPmeasurement from that UE. The eNB can then use those measurements, forexample a collection of data points which can be collected from theplurality of UEs (i.e. crowd sourced data) to create a function whichbest estimates the expected RSRP value for all TA values or distanceswhere ‘d’=TA*c/2. The expected RSRP value can be determined according toEquation 14:

˜RSRP=RSRPEst(d=TA*c/2)  (14)

According to embodiments, using this estimated RSRP, the eNB can thenevaluate the functions that can be used to generate ΔRSRP_ThNeg andΔRSRP_ThPos for a particular Δd. For example, ΔRSRP_ThPos can bedetermined according to Equation 15 and ΔRSRP_ThNeg can be determinedaccording to Equation 16.

ΔRSRP_ThPos=RSRPEst(d _(i))−RSRPEst(d _(i) −Δd)  (15)

ΔRSRP_ThNeg=RSRPEst(d _(i))−RSRPEst(d _(i) −Δd)  (16)

According to some embodiments, the UE could also generate the RSRPEst(d) function, however the UE would have few RSRP vs ‘d’ data points thatcould be used for the estimation of an appropriate function for RSRPEst(d).

The functions presented above are examples of functions that can providea means for the determination of the thresholds for evaluation of TAvalidity. It will be readily understood that a variety of otherfunctions or equations can be used for the determination of ΔRSRP_ThNegand ΔRSRP_ThPos, and these can include the expressions presented inEquation 10 and Equation 11 above.

Given the above discussion relating to the evaluation of the positivethreshold and negative threshold for the evaluation of the validity ofthe TA currently known to a UE, the eNB or the UE can be configured forthe evaluation of these thresholds. In some embodiments, the UE willdetermine the thresholds and thus would have access thereof in order forthe determination of the validity of the TA. In some embodiments, whenthe eNB estimates the TA, the eNB can calculate the ΔRSRP_ThNeg andΔRSRP_ThPos thresholds and send these thresholds directly to the UE.These thresholds could be sent via UE specific signalling for example.

For example, in some embodiments, the eNB can be configured to calculatethe RSRP change thresholds for a range of TA values and send thesedetermined thresholds to the UE during PUR configuration to save as atable so that by sending only TA updates, for example in PUR responsesand configuration updates, the UE can look up the matching RSRP changethresholds for evaluation of the validity of a TA value currently knownto the UE.

In other embodiments, the RSRPEst function, namely a more generalizedfunction for the determination of the threshold, can be estimated by theeNB and subsequently broadcasted for all UEs to use thereby. Accordingto embodiments, the generalized function can be configured as apolynomial or a piecewise continuous equation or other suitable equationconfiguration as would be readily understood. The broadcasting of thegeneralized function can require less overall signaling for provisionthereof to the UEs, however this generalized function may be lessflexible and possibly less accurate than UE specific thresholds.

FIG. 5 is a schematic diagram of an electronic device 800 that mayperform any or all of the steps of the above methods and featuresdescribed herein, according to different embodiments of the presentinvention. For example, a UE may be configured as the electronic device.Further, a base station, eNB, gNB or NB may be configured as theelectronic device 800.

As shown, the device includes a processor 810, memory 820,non-transitory mass storage 830, I/O interface 840, network interface850, and a transceiver 860, all of which are communicatively coupled viabi-directional bus 870. According to certain embodiments, any or all ofthe depicted elements may be utilized, or only a subset of the elements.Further, the device 800 may contain multiple instances of certainelements, such as multiple processors, memories, or transceivers. Also,elements of the hardware device may be directly coupled to otherelements without the bi-directional bus.

The memory 820 may include any type of non-transitory memory such asstatic random access memory (SRAM), dynamic random access memory (DRAM),synchronous DRAM (SDRAM), read-only memory (ROM), any combination ofsuch, or the like. The mass storage element 830 may include any type ofnon-transitory storage device, such as a solid state drive, hard diskdrive, a magnetic disk drive, an optical disk drive, USB drive, or anycomputer program product configured to store data and machine executableprogram code. According to certain embodiments, the memory 820 or massstorage 830 may have recorded thereon statements and instructionsexecutable by the processor 810 for performing any of the aforementionedmethod steps described above.

As will be readily understood by the description above, the terms basestation and network node can be interchangeably used to define anevolved NodeB (eNB), a next generation NodeB (gNB) or other base stationor network node configuration.

It will be appreciated that, although specific embodiments of thetechnology have been described herein for purposes of illustration,various modifications may be made without departing from the scope ofthe technology. The specification and drawings are, accordingly, to beregarded simply as an illustration of the invention as defined by theappended claims, and are contemplated to cover any and allmodifications, variations, combinations or equivalents that fall withinthe scope of the present invention. In particular, it is within thescope of the technology to provide a computer program product or programelement, or a program storage or memory device such as a magnetic oroptical wire, tape or disc, or the like, for storing signals readable bya machine, for controlling the operation of a computer according to themethod of the technology and/or to structure some or all of itscomponents in accordance with the system of the technology.

Acts associated with the method described herein can be implemented ascoded instructions in a computer program product. In other words, thecomputer program product is a computer-readable medium upon whichsoftware code is recorded to execute the method when the computerprogram product is loaded into memory and executed on the microprocessorof the wireless communication device.

Acts associated with the method described herein can be implemented ascoded instructions in plural computer program products. For example, afirst portion of the method may be performed using one computing device,and a second portion of the method may be performed using anothercomputing device, server, or the like. In this case, each computerprogram product is a computer-readable medium upon which software codeis recorded to execute appropriate portions of the method when acomputer program product is loaded into memory and executed on themicroprocessor of a computing device.

Further, each step of the method may be executed on any computingdevice, such as a personal computer, server, PDA, or the like andpursuant to one or more, or a part of one or more, program elements,modules or objects generated from any programming language, such as C++,Java, or the like. In addition, each step, or a file or object or thelike implementing each said step, may be executed by special purposehardware or a circuit module designed for that purpose.

It is obvious that the foregoing embodiments of the invention areexamples and can be varied in many ways. Such present or futurevariations are not to be regarded as a departure from the spirit andscope of the invention, and all such modifications as would be obviousto one skilled in the art are intended to be included within the scopeof the following claims.

We claim:
 1. A method for evaluation of validity of a timing advance forenabling use of preconfigured uplink resources (PUR), the methodcomprising: receiving, by a user equipment (UE), data enablingdetermination of a measured change in a reference signal received power(RSRP); and upon determination that the measured change in the RSRP doesnot exceed a positive change threshold, transmitting, by the UE, usingPUR.
 2. The method of claim 1, further comprising, only upondetermination that the measured change in the RSRP does not exceed anegative change threshold, transmitting, by the UE, using PUR.
 3. Themethod of claim 1, wherein the positive change threshold is defined fora specific UE.
 4. The method of claim 2, wherein the negative changethreshold is defined for a specific UE.
 5. The method of claim 1,further comprising receiving, by the UE, a table indicative of acorrelation between TA and RSRP change thresholds and storing, by theUE, the table.
 6. The method of claim 1, wherein when the positivechange threshold is negative, receiving, by the UE from an evolved NodeB (eNB), a transmission indicating nonuse of RSRP to validate the timingadvance, unless the UE is closer to the eNB than a predefined distancechange threshold.
 7. The method of claim 1, wherein upon determinationthat the positive change threshold is negative, using, by the UE, randomaccess channel (RACH) mechanisms, unless the UE is closer to the eNBthan a predefined distance change threshold.
 8. The method of claim 2,wherein when the negative change threshold is positive, receiving, bythe UE from an evolved Node B (eNB), a transmission indicating nonuse ofRSRP to validate the timing advance.
 9. The method of claim 2, whereinupon determination that the negative change threshold is positive,using, by the UE, random access channel (RACH) mechanisms.
 10. Themethod of claim 2, wherein a single threshold is used as the positivechange threshold and the negative change threshold.
 11. The method ofclaim 2, wherein the positive change threshold and the negative changethreshold have a same value.
 12. A user equipment (UE) comprising: aprocessor; and a non-transient memory for storing instructions that whenexecuted by the processor cause the UE to be configured to: receive dataenabling determination of a measured change in a reference signalreceived power (RSRP); and upon determination that the measured changein the RSRP does not exceed a positive change threshold, transmit usingpreconfigured uplink resources (PUR).
 13. The UE of claim 12, whereinthe instructions when executed by the processor further cause the UE tobe configured to only upon determination that the measured change in theRSRP is less than a negative change threshold, transmitting, by the UE,using PUR.
 14. The UE of claim 12, wherein the positive change thresholdis defined for a specific UE.
 15. The UE of claim 13, wherein thenegative change threshold is defined for a specific UE.
 16. The UE ofclaim 12, wherein the instructions when executed by the processor causethe UE to be configured to receive a table indicative of a correlationbetween TA and RSRP change thresholds and store the table.
 17. The UE ofclaim 12, wherein when the positive change threshold is negative, theinstructions when executed by the processor further cause the UE to beconfigured to receive from an evolved Node B (eNB), a transmissionindicating nonuse of RSRP to validate the timing advance, unless the UEis closer to the eNB than a predefined distance change threshold. 18.The UE of claim 12, wherein upon determination that the positive changethreshold is negative, the instructions when executed by the processorfurther cause the UE to be configured to use random access channel(RACH) mechanisms, unless the UE is closer to the eNB than a predefineddistance change threshold.
 19. The UE of claim 13, wherein when thenegative change threshold is positive, the instructions when executed bythe processor further cause the UE to be configured to receive from anevolved Node B (eNB), a transmission indicating nonuse of RSRP tovalidate the timing advance.
 20. The UE of claim 13, wherein upondetermination that the negative change threshold is positive, theinstructions when executed by the processor further cause the UE to beconfigured to use random access channel (RACH) mechanisms.